1. You accept feedback gracefully

Remember when your teacher would comment on your report card, "Dan frequently calls out in class," or "Sally has difficulty sharing with classmates," and you'd read it and have the urge to shout back, "DO NOT"?

If you've managed to curb that impulse, good job! Because if you haven't, and you're in a performance review with your boss, you just might get fired.

"An amazing skill (which you can learn through practice) is to set aside your emotional response in the moment and focus on the information presented to you. Some of it will be valid and some of it invalid but let your brain decide that, not your ego."

Depending on what kind of feedback you're receiving, there are different strategies for responding with a cool head. For example, if your boss points out what she thinks is an error and you're not sure she's correct, you can say, "I hadn't thought of that, and I'm going to look into it right away."

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2. You apologize sincerely

Owning up to your mistakes — without getting defensive — can be a sign of maturity.

The apology you give "needs to be sincere, not qualified, not quantified, and also needs to outline how X will not happen again," Keyani says.

Keyani gives an example of what you might say if you were tardy for an appointment:

I'm sorry I was late for the meeting. It must have been frustrating because you spent a lot of time preparing and got up early. I did a poor job accounting for traffic and didn't give myself enough buffer. That is my bad and I'm going to give myself an extra 10 minutes instead of five moving forward.

3. You manage your time wisely

There will probably never be a time in your life when you aren't juggling multiple personal and professional priorities. Adulthood is about accepting that, and learning to cope with the burden through prioritization.

Perhaps the most important time-management lesson is that you should stick with one task at a time. Research suggests that multitasking is generally counterproductive because the brain expends energy as it readjusts its focus from one activity to another.

You'd be wise, too, to limit the hours you spend working. Decades ago, Henry Ford discovered that productivity started to decline after employees logged more than 40 hours per week. Other research suggests that, after three weeks, 60-hour workweeks become less productive.

According to Glasrud, the best way to muster up the confidence to turn down a request is to recognize that there "are some things you can never have back. Your time, your health, your virtue, your life. Don't mess around with those things. It's fine for people to ask — most likely, in their mind, they're trying to help introduce you to a great person or opportunity or meaningful cause. And it's just as fine for you to say 'no.'"

5. You empathize with others

A number of Quora users mentioned the importance of learning to empathize with other people — to listen to them and try to see things from their perspective.

Psychologists say that empathy is a fundamental part of human interaction. In fact, research suggests that empathetic individuals are more likely to succeed in the workplace. They generally get along better with colleagues and achieve higher company rank.

NBC

6. You make friends in any environment

It might have worked in high school, but being shy is no longer a valid excuse for not talking to anyone. The ability to forge relationships — without leaving them to chance — is one of the most important skills of adulthood, Tahsin Mayeesha suggests.

That skill is especially important to develop during young adulthood, once you're off the college campus, where it's generally easy to forge close friends.

One way to make friends as a grown-up is to trade confidences. Research suggests that "self disclosure" predicts liking, closeness, and relationship-building. Another, surprisingly simple, tactic is to simply spend more time with the people you'd like to befriend. According to the "mere exposure effect," we tend to like things and people we're familiar with.

7. You stick to a budget

There are few worse feelings than logging into your bank account and realizing that you have way fewer funds than you thought. And that next month's planned vacation is definitely out.

If you've managed to avoid that feeling (for the most part), because you stick to a weekly or monthly budget, you're definitely on your way to full-fledged adulthood.

"It's amazing how many people can't do the simplest of things — like balance a checkbook, fill out a tax form, make sure that there's more coming in than going out, [set] aside reserves for contingencies," writes Miles Fidelman.

Let's start with making sure that "there's more coming in than going out," which is essentially about adhering to a budget. We rounded up the best budgeting tips from readers who have shared their budgets with Business Insider.

For example, you'll want to anticipate any major costs in the near future — like if you're planning to have a kid or go back to school. It's also wise to set aside an emergency fund with several months' worth of expenses in case the unexpected occurs.

8. You spend time alone

I approach being alone with a very specific list of things that only I want to do. I go to weird museums, see movies that only I want to see, take mini-road trips, or see bands that only I like.

If you're planning to live alone, which many Americans do, you should accept that you will occasionally feel lonely. It's nothing to be ashamed of or upset about, but it might be a signal that you should incorporate some more socializing into your daily schedule.

9. You negotiate your salary

One survey found that nearly half of all workers accept the first salary offer given to them. But part of being a grownup is mustering the courage to ask for what you really want — and negotiate until you get closer to that number.

10. You cook basic meals

You don't need to be Julia Child to sustain yourself or impress fellow guests at a potluck. But subsisting on cereal is hardly a healthful alternative.

"Know how to cook at least five dishes," writes Erin Nakano O’Quinn. "These are likely to be dependent upon the culture you live in, but be able to cook at least one vegetarian dish, a breakfast dish, a dish that you can serve to a group of people, a dessert, and a starch. Try to be able to do these without a cookbook, and you can look like a rockstar wherever you go."

11. You make small talk

Being a working professional means you'll probably have to attend your fair share of industry events, networking nights, and conferences. And chances are good that you won't know many of the people there.

One of the most important rules of making small talk is to demonstrate interest in your conversation partner and let him share information about himself. Another tactic is to flatter your partner, so that she feels better about herself after having spoken to you.

12. You display grit

You push, all the time. You are constantly looking for how to do things, how to do them better, but with a holistic approach to your life. Things have places, you have goals. You can always be busy, always find new work because you have developed grit. You love what you do and you can think of new ideas in your sleep.

Angela Duckworth, a University of Pennsylvania psychologist and author of the book "Grit," says that grit is a combination of passion and perseverance that strongly influences your success in life.

Fortunately, Duckworth also says that your grit profile can change — and that people generally get grittier as they age — so don't worry if you aren't yet as passionate or as perseverant as you'd like.

13. You ask for help

This one might seem counterintuitive — isn't adulthood about being independent?

Yes and no. While you don't need to solicit everyone's opinion all the time, there's nothing shameful about asking for a little advice or assistance, especially at work.

In fact, research suggests that soliciting advice can make you look more competent. That's likely because people feel flattered that you turned to them in the first place.

If you're looking for general career advice, entrepreneur and author Tim Ferriss told Inc., it's best to ask someone who became successful quickly and against the odds, instead of someone with a more conventional story.

15. You aren't afraid to meet potential dates

Approaching an attractive stranger and starting a conversation is a terrifying prospect for pretty much every normal person.

Adults are able to accept their nervousness and approach that stranger anyway — whether online or IRL.

In either situation, there are ways to reduce your anxiety and the chance that you'll come across as a bumbling fool.

One study found that men tend to prefer direct approaches, like "You're cute — can I buy you a drink?" Women, on the other hand, generally prefer more open-ended questions, like "What do you think of this band?"

Very few people in the study said that they preferred standard pick-up lines — so it's best to avoid those, no matter how clever you think you are.

16. You give a solid elevator pitch

"Concise and clear delivery of your ideas should be #1 in your skill set. In our noisy world, people are too busy to listen to you longer than 30 seconds.

"Brief and persuasive speech that you use to spark interest in who you are or what you do can become your secret weapon to landing a job of your dream or establishing powerful business ties. A skill to get your points across quickly is essential and definitely worth mastering."

17. You manage up

Following orders is the easy part. As you progress in your career, you'll learn that your boss needs to be managed, too.

In other words, if you want your boss to love you, it's important to figure out what will make them look good to their bosses — and then help them achieve those goals.

The term is "managing up," and we learned about it from Dave Kerpen, founder and CEO of Likeable Local. It will make your life and your relationship with your boss a whole lot easier.

"Think of managing up as the 'Platinum Rule' for organizations," Kerpen writes in his book, "The Art of People." "Think like your manager and you will reap the benefits of getting your way when you need it most."

18. You write clearly

Whether you're sending an email to a friend or submitting a project report to your boss, the ability to convey your thoughts in writing is crucial.

"Learning to write well involves not just mastery of grammar," says Janis Butevics, "but the development of the ability to organize one's thoughts into a coherent form and target it to an audience in the most effective way possible."

If you're hoping to become a better writer, take a tip from Benjamin Franklin, who reportedly taught himself to write well by copying the style of essays published in the English gentleman's magazine The Spectator. Specifically, Franklin would read an essay, summarize it, and then try writing his own version to see if his was better than the original.

19. You practice self-compassion

Beating yourself up over your failures won't get you anywhere. Once you've learned that, you'll be en route to a healthy, mature lifestyle.

According to Emma Seppala, science director of Stanford's Center for Compassion and Altruism Research and Education, you should treat yourself as you would treat a colleague or friend who has failed. For example, you might remind yourself that mistakes are normal and that they don't mean you're a bad person.

One strategy for practicing self-compassion is to write yourself a comforting letter — again, as though you're writing to a friend. Another strategy is to come up with a self-compassion phrase that you repeat when you're struggling.

By caring for yourself the same way you care for other people, Seppala says you'll experience less anxiety and depression and you'll have a better chance of bouncing back from stressful situations.